Growing watermelon with a lack of space is a viable possibility with a strong, durable trellis. The trick is to secure the watermelon to the trellis with a mesh produce bag, nylon stockings, cotton strips, etc., so that when they grow heavy they won’t fall of the vine due to shear weight. One can either drop the watermelon inside the bag or secure it in a hammock like a sling (Figure 1). I am personally trying out this alternative growing method in a community garden where we cannot plant directly into the ground. Figure 2 depicts a trellis I constructed out of donated bamboo and nylon string.
I am using mesh bags and nylon stockings, and so far the results have been positive. The bags have held the weight of the watermelon and are secured tightly. The only problem I have encountered is blossom-end rot
and have not had any more watermelon obtain blossom-end rot using the bags. For more information on growing watermelon visit http://gardeningsolutions.ifas.ufl.edu/plants/edibles/fruits/watermelon.html and to stay up to date on my watermelons and what I am doing in my gardens, visit http://pasco.ifas.ufl.edu/gardening/communitygardensindex.shtml
Photo credits Figure 1:https://abundantminigardens.com/sample-garden-layouts
Debra Jones http://gardeningjones.com/2015/01/11/the-delightful-sugar-baby-watermelon/